The present invention relates to a sheet ejection device that aligns a position of a sheet in its width direction on a sheet ejection tray, an image forming apparatus equipped with the sheet ejection device and a sheet finisher equipped with the sheet ejection device.
In a sheet ejection device that ejects a large quantity of sheets, the large quantity of sheets are ejected on a sheet ejection tray and are stacked, and after that, a bundle of sheets is given processing treatment. Therefore, the plenty of sheets are sometimes conveyed to another processor. In that case, a bundle of sheets prior to the processing treatment is required to have high compatibility. Accordingly, there is known a sheet ejection device equipped with an alignment member that aligns a bundle of sheets stacked on the sheet ejection tray.
Further, there is available a sheet ejection device by which a bundle of sheets is moved through shifting to a different position in the direction perpendicular to a sheet ejecting direction in a unit of one set of sheets so that dividing of sheets stacked on the sheet ejection tray in a unit of one set may become easy. In the sheet ejection device having the shifting function of this kind, high compatibility is required for each bundle of sheets at each shifting position.
Further, an image forming system that contains an image forming apparatus and is capable of processing at high speed is in a trend to be used as a shortrun printing apparatus, and when it is used as a shortrun printing apparatus, there is a growing trend wherein the image forming system is required to have capabilities to align a sheet on which an image has been formed with a sheet which has been processed by another apparatus to eject them.
In Unexamined Japanese Patent Application Publication No. 2002-211829, there is proposed to shift under the highly-aligned configuration and thereby to integrate by providing a shifting function on a sheet ejection tray.
In the case of a high-speed image forming apparatus and an image forming system composed of a high-speed image forming apparatus and a sheet finisher, a large quantity of sheets are integrated on a sheet ejection tray.
An integrated sheet is conveyed from a sheet ejection tray to another processing station, to be sent to the succeeding processing progress.
When conveying a sheet from a sheet ejection tray to the succeeding processing progress, the sheet is taken out of the sheet ejection tray manually in many cases.
However, handling of a sheet having a large volume and large mass is not easy, and there are sometimes generated accidents including destroyed alignments caused by contact between aligned sheets and surrounding mechanical parts, and injuries caused by contact between an operator's hand and mechanical parts.
In particular, when an alignment member is provided at the position near a sheet ejection tray, the number of chances to come in contact with the alignment member grows greater.
The alignment device disclosed in Unexamined Japanese Patent Application Publication No. 2002-211829 is not equipped with a safety device for the aforesaid accidents.